Objective: To gain better understanding of basic mechanisms (cellular and humoral) governing the immune response to tumor specific antigesn. Approach: Human neoplasms, as well as chemically and virally induced animal tumors, are studied with an emphasis on various aspects of cell-mediated immune reactions to tumor antigens, e.g., with respect to lymphoic cells reacting. The various tumor specific and tumor associated antigens present in human tumors are being studied with emphasis on whether immunity to such antigens (common to human tumors of the same histological type or unique to each neoplasms) correlates with the patients' clinical course, and what the effects of therapy are on the immune responses to various tumor antigens in human neoplasms.